Photoluminescent porous aerogel monoliths containing ZnEu-complex: the first example of aerogel modified with a heteronuclear metal complex

A procedure for the chemical immobilization of a new Zn-II-Eu-III heterobimetallic complex in the SiO2 aerogel matrix has been developed. In this Zn-Eu complex, a peripheral non-luminescent Zn ion acts as a binder to a silica matrix and prevents direct interaction of rare-earth ions with OH- and NH- groups in the silica matrix, which would have a detrimental effect on the luminescence of lanthanides. The procedure includes the synthesis of complexes, co-gelation of the obtained complex with SiO2 sol, the washing of lyogels, and their subsequent supercritical drying in CO2. The composition and properties of the obtained aerogels were investigated using a low-temperature nitrogen adsorption technique, helium pycnometry, FTIR, Raman, UV-visible, and luminescence spectroscopy, XPS, PXRD, SEM, TEM, TGA combined with mass spectrometry, and small-angle neutron scattering. The aerogels modified with the Zn-II-Eu-III complex demonstrated strong red luminescence upon excitation with UV light.